Monday 23 September 2013

Science: How to make a spinner!

This follows on from the make a wing project as it works partly due to aerofoil again and partly because it's about how things fly!
This time we are learning about propellers and how they work.
Honi's spinner she made herself with very little help indeed!
In this project we are making  a simple paper propeller called a spinner.  Here's how to make it...

Take a piece of paper and cut it into a rectangle that is 15cm by 9cm. 
Draw a T shape on it like this... 
Carefully cut along the 13cm lines you have made.
Fold one of the strips forward and one backwards like this:

Lift it up as high as you can and let it fall...

How does it work?
As the spinner falls, moving air rushes past the blades.  This is what makes the spinner revolve (spin round).

Propellers work in in two different ways: 
1.  When a propeller spins, it makes air move past it (propeller drive craft use this effect to produce thrust).
2.   Moving air makes the propeller spin.

Where else can we see this? In nature, seeds from trees like the sycamore tree have twin propeller blades.  As they drop from the tree they sin and catch the wind, this is how the trees seeds are dispersed - the seeds use this to be carried away and land further away so they have room to grow into another tree.

Other things to try...

Try putting a paper clip at the bottom of the propeller on the centre strip.  Does it work better?

Now try moving the paperclip and experiment with what makes the spinner work best!

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